Image sensor comprising array of colored pixels

ABSTRACT

An image sensor includes a Bayer pattern-type pixel array including a plurality of Bayer pattern-type extended blocks each having first to fourth pixel blocks, each of the first to fourth pixel blocks including first to fourth pixels, the first and fourth pixels of the first and fourth pixel blocks being configured to sense green light, the first and fourth pixels of the second and third pixel blocks being configured to sense red light and blue light, respectively, and the second and third pixels of the first to fourth pixel blocks being configured to sense white light, and a signal processing unit merging Bayer pattern color information generated from the first and fourth pixels of the first to fourth pixel blocks, and the Bayer pattern illuminance information generated from the second and third pixels of the first to fourth pixel blocks.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. application Ser. No.17/142,652, filed on Jan. 6, 2021, which claims the benefit under 35 USC119(a) of Korean Patent Application No. 10-2020-0053244 filed on May 4,2020 in the Korean Intellectual Property Office, the entire disclosureof each of which is incorporated herein by reference for all purposes.

BACKGROUND

Some example embodiments relate to an image sensor.

Image sensors that capture an image of an object and convert the imageinto an electrical signal are not only used in consumer electronics suchas digital cameras, mobile phone cameras, and portable camcorders, butalso in cameras mounted in automobiles, security devices, and/or robots.Such an image sensor includes a pixel array, and each pixel included inthe pixel array may include a light sensing element.

To increase the resolution of the image sensor, the size of the pixel iscontinuously reduced, and the sensitivity of the light sensing elementof each pixel may be reduced due to the reduction in the pixel size. Asa result, the image quality of the image may deteriorate.

SUMMARY

Some example embodiments provide an image sensor in which a dynamicrange (DR) and/or a signal-to-noise ratio (SNR) may be improved bycompensating for low sensitivity of color pixels.

According to some example embodiments, an image sensor includes a Bayerpattern-type pixel array including a plurality of Bayer pattern-typeextended blocks each having first to fourth pixel blocks arranged in abig 2×2 matrix, each of the first to fourth pixel blocks including firstto fourth pixels arranged in a small 2×2 matrix, the first and fourthpixels of the first and fourth pixel blocks configured to sense greenlight, the first and fourth pixels of the second and third pixel blocksconfigured to sense red light and blue light, respectively, and thesecond and third pixels of the first to fourth pixel blocks configuredto sense white light; and, a signal processing circuitry configured togenerate Bayer pattern color information by binning signals of the firstand fourth pixels of the first to fourth pixel blocks, to generate Bayerpattern illuminance information by binning signals of the second andthird pixels of the first to fourth pixel blocks, and to generate acolor image by merging the Bayer pattern color information and the Bayerpattern illuminance information.

According to some example embodiments, an image sensor includes a pixelarray including a plurality of Bayer pattern-type extended blocks eachhaving first to fourth pixel blocks, the first to fourth pixel blocksrespectively including a plurality of pixels arranged in a plurality ofrows and a plurality of columns, the plurality of pixels being dividedinto first and second groups each having at least two pixels, pixels ofa first group of the first and fourth pixel blocks respectivelyconfigured to sense first color light, pixels of a first group of thesecond pixel block configured to sense second color light, pixels of afirst group of the third pixel configured to sense third color light,and pixels of a second group of the first to fourth pixel blocksrespectively configured to sense light of a wavelength band wider than awavelength band of each of at least second and third color light,respectively, and a signal processing circuitry configured to generateBayer pattern color information by binning signals of pixels of thefirst group of the first to fourth pixel blocks, to generate Bayerpattern illuminance information by binning signals of pixels of a secondgroup of the first to fourth pixel blocks, and to generate a color imageby merging the Bayer pattern color information and the Bayer patternilluminance information.

According to some example embodiments, an image sensor includes a pixelarray including a plurality of Bayer pattern-type extended blocks eachhaving first to fourth pixel blocks arranged in a big 2×2 matrix, eachof the first to fourth pixel blocks including first to fourth pixelsarranged in a small 2×2 matrix, the first and fourth pixels of the firstand fourth pixel blocks configured to receive light of a first color,the first and fourth pixels of the second and third pixel blocksconfigured to receive light of second and third colors, respectively,and the second and third pixels of the first to fourth pixel blocksconfigured to receive white light, and a signal processing circuitryconfigured to generate Bayer pattern color information by binningsignals of the first and fourth pixels of the first to fourth pixelblocks, and to generate the Bayer pattern illuminance information bybinning signals of the second and third pixels of the first to fourthpixel blocks. The first and fourth pixel blocks are arranged in a firstdiagonal direction, the second and third pixel blocks are arranged in asecond diagonal direction, the first and fourth pixels are arranged inone of the first diagonal direction and the second diagonal direction,and the second and third pixels are arranged in the other of the firstdiagonal direction and the second diagonal direction.

BRIEF DESCRIPTION OF DRAWINGS

The above and other aspects, features, and advantages of the exampleembodiments will be more clearly understood from the following detaileddescription, taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a block diagram illustrating the structure of an image sensoraccording to some example embodiments;

FIG. 2 is a block diagram schematically illustrating an image sensoraccording to some example embodiments;

FIG. 3 is a plan view illustrating a pixel array employable in an imagesensor according to some example embodiments;

FIGS. 4A and 4B respectively illustrate Bayer pattern color (e.g., RGB)information and illuminance information generated by signal processingof an image sensor according to some example embodiments;

FIG. 5 illustrates a Bayer pattern color image in which a color arraypattern illustrated in FIG. 4A and the illuminance informationillustrated in FIG. 4B are merged.

FIG. 6 is a partial plan view illustrating a pixel array illustrated inFIG. 1 .

FIG. 7 illustrates an example of a driving circuit corresponding to thepixel array illustrated in FIG. 6 .

FIG. 8 is a plan view illustrating a pixel array (including autofocusingpixels) according to some example embodiments;

FIG. 9 is a cross-sectional view illustrating an autofocusing pixel ofthe pixel array illustrated in FIG. 8 .

FIG. 10 is a plan view illustrating a pixel array (including anautofocusing pixel) according to some example embodiments;

FIG. 11 is a cross-sectional view illustrating an autofocusing pixel ofthe pixel array illustrated in FIG. 10 .

FIG. 12 is a plan view illustrating a pixel array employable in an imagesensor according to some example embodiments; and

FIGS. 13A and 13B respectively illustrate Bayer pattern colorinformation and illuminance information generated by signal processingof an image sensor according to some example embodiments.

DETAILED DESCRIPTION OF SOME EXAMPLE EMBODIMENTS

Hereinafter, various example embodiments will be described in detailwith reference to the accompanying drawings.

FIG. 1 is a block diagram illustrating the structure of an image sensoraccording to some example embodiments.

Referring to FIG. 1 , an image sensor 500 according to some exampleembodiments may include a pixel array 100, a signal processing unit 200,and a control unit 300. The image sensor 500 may further include amemory 400.

As illustrated in FIG. 3 to be discussed below in more detail, the pixelarray 100 employed in some example embodiments may have a plurality ofpixels PX constituting/included in an extended Bayer pattern block EB.The extended Bayer pattern block EB may be respectively comprised offour pixel blocks PB1, PB2, PB3 and PB4, e.g. arranged adjacently asillustrated. Each of the plurality of pixels PX may include an opticalsensing element that converts an optical signal into an electricalsignal. For example, the light sensing element may be or include orcorrespond to a photodiode.

The plurality of pixels PX may include red, green, and blue pixels R, Gand B configured to receive red, green, and blue light, respectively,and white pixels W, configured to receive white light. The white pixel Wmay have higher sensitivity than the red, green, and blue pixels R, G,and B. The red, green and blue pixels R, G, and B include red, green,and blue filters, respectively to receive light in a specific wavelengthband (e.g. the wavelength band of red, green, and blue light,respectively), whereas the white pixel W may receive the light coveringthe wavelength band of red, green, and blue without a filter. The red,green, and blue pixels R, G, and B and the white pixel W receive lightof one of red, green, blue, and white in the unit of a pixel through amicro lens (see, e.g., micro lens 109 in FIG. 8 ), and the opticalsensing element may generate and output electrical signals correspondingto the intensity of light received by photoelectric conversion.

In some example embodiments, the plurality of pixels PXconstituting/included in the pixel array 100 may be arranged in aplurality of rows and a plurality of columns. For example, FIG. 3illustrates a form in which 64 pixels PX are arranged in an 8×8 matrixfor convenience of description, but the form may have an array (e.g.,1920×1080) of one million or more pixels. In detail, as described above,the arrangement as described above may constitute/be included in a pixelblock (PB1, PB2, PB3, PB4) unit and an extended Bayer pattern block (EB)unit.

In detail, the pixel array 100 may include a plurality of extended Bayerpattern blocks EB respectively having first to fourth pixel blocks PB1,PB2, PB3 and PB4 arranged in a 2×2 matrix (e.g. in a larger matrix),e.g. arranged adjacently as illustrated. The first to fourth pixelblocks PB1, PB2, PB3 and PB4 may be arranged in a larger matrix, and mayeach include first to fourth pixels PX1, PX2, PX3 and PX4 arranged in asmaller 2×2 matrix, e.g. arranged adjacently as illustrated.

In each of the plurality of extended Bayer pattern blocks EB employed insome example embodiments, the first and fourth pixel blocks PX1 and PX4may be arranged in a first diagonal (DL1) direction, and the second andthree pixel blocks PX2 and PX3 may be arranged in a second diagonal(DL2) direction.

Further, the first and fourth pixels PX1 and PX4 of the first and fourthpixel blocks PB1 and PB4 may be green pixels G configured to sense greenlight. The first and fourth pixels PX1 and PX4 of the second and thirdpixel blocks PB2 and PB3 may be red and green pixels R and G configuredto sense red light and blue light, respectively. The second and thirdpixels PX2 and PX3 of the first to fourth pixel blocks PB1, PB2, PB3 andPB4 may be white pixels W configured to sense white light.

In some example embodiments, in each of the first to fourth pixel blocksPB1, PB2, PB3, and PB4, the first and fourth pixels PX1 and PX4 may bearranged in the direction of the first diagonal DL1, and the second andthird pixel blocks PX2 and PX3 may be arranged in the direction of thesecond diagonal DL2 direction. In some example embodiments, the first tofourth pixel blocks PB1, PB2, PB3 and PB4 may be arranged in a directionopposite to the direction in this example embodiment. For example, thefirst and fourth pixels PX1 and PX4 are arranged in the second diagonalDL2 direction, and the second and third pixel blocks PX2 and PX3 may bearranged in the first diagonal DL1 direction.

As such, in some example embodiments, the first and fourth pixels PX1and PX4 are provided as color pixels indicated by R, G, and B, and thesecond and third pixels PX2 and PX3 may be provided as illuminancesensing pixels to improve sensitivity. The illuminance sensing pixel maybe configured to receive light in a band wider than the wavelength bandof the color pixel, and may include, for example, a yellow pixel and/ora white pixel W.

According to some example embodiments, a “pixel block” refers to a unitin which a plurality of color pixels (e.g., PX1 and PX4) and a pluralityof luminance sensing pixels (e.g., PX2 and PX3) are combined andarranged, and “extended Bayer pattern block” refers to a unit in whichfour pixel blocks PB are arranged in a Bayer pattern. In some exampleembodiments, in terms of color pixels of the first to fourth pixelblocks PB1, PB2, PB3, and PB4, the extended Bayer pattern block EB maybe understood to implement a Bayer array pattern of R-G-G-B. Inaddition, the Bayer pattern color pattern information BP1 illustrated inFIG. 4A may have a Bayer array pattern of R-G-G-B corresponding to sucha Bayer array.

As illustrated in FIG. 1 , output signals of the pixel array 100 areinput to a binning pattern generation unit 240 of the signal processingunit 200. The binning pattern generation unit 240 may bin RGBW arraydata obtained from the pixel array 100 into a color signal comprised ofRGB and an illuminance signal comprised of W, and may generate colorpattern information BP1 and illuminance pattern information BP2generated from the binned color signal and illuminance signal,respectively. Since the color pattern information BP1 and theilluminance pattern information BP2 are respectively generated throughsuch binning, signal processing such as gain and/or offset may beindependently performed on the two pattern information BP1 and BP2.

The color pattern information BP1 and the illuminance patterninformation BP2 generated by the binning pattern generation unit 240have a Bayer pattern as illustrated in FIGS. 4A and 4B. The respectivepatterns constituting the color pattern information BP1 and theilluminance pattern information BP2 may be or correspond to or be basedon data based on/associated with signals obtained from one pixel blockPB of the pixel array 100.

For example, green pattern information of a first row and a first columnof the color pattern information BP1 may be obtained from the signals ofthe two green pixels PX1 and PX4 of the first pixel block PB1. Whitepattern information of a first row and a first column of the illuminancepattern information BP2 may be obtained from signals of the remainingtwo white pixels PX2 and PX3 of the first pixel block PB1.

As described above, since respective patterns of the color patterninformation BP1 and the illuminance pattern information BP2 aregenerated from one pixel block PB comprised of four pixels PX, theresolution (m×n) of the Bayer pattern color information may be ¼ (onequarter) of the resolution (2m×2n) of the pixel array 100. Theilluminance pattern information BP2 may also have a Bayer pattern in thesame arrangement as the color pattern information BP1.

In the binning pattern generation unit 240, the color patterninformation BP1 and the illuminance pattern information BP2 having thesame Bayer pattern are input to a pattern merging unit 280 of the signalprocessing unit 200. The color pattern information BP1 and theilluminance pattern information BP2 may be merged to provide a colorimage MCI having the same resolution as the color pattern informationBP1 (as illustrated in FIG. 5 ). The merging process may be performed insuch a manner that patterns in positions corresponding to each other inthe color pattern information BP1 and the illuminance patterninformation BP2 one-to-one merge with each other (e.g. are overlaid witheach other). The respective colors R, G, and B of the color patterninformation BP1 may have improved sensitivity characteristics by theilluminance data at the corresponding position of the illuminancepattern information BP2, thereby providing a color image MCI havingconverted colors R′, G′ and B′.

As described above, according to some example embodiments, the colorpattern information BP1 obtained from the respective first and fourthpixels PX1 and PX4 is improved, e.g. greatly improved in sensitivitycharacteristics such as SNR and/or DR by binned illumination informationBP2, and as a result, since respective pattern data of the illuminancepattern information BP2 is information obtained from white pixelslocated/arranged adjacent in the same pixel block PB as that of thefirst and fourth pixels PX1 and PX4 associated with the color signal tobe merged, the sensitivity may be appropriately improved according tothe environment, e.g. neighborhood, of relevant pixels.

In some example embodiments, a corrected color image MIC may be storedin the memory 400. The control unit 300 may control the signalprocessing unit 200 to perform a series of processes. For example, aprogram including machine-readable instructions that executes a seriesof processes may be stored in the memory 400, and the control unit 300may control the series of processes by executing a program read from thememory 400.

According to some example embodiments, the color pattern information BP1and the illuminance pattern information BP2 have a resolution of ¼ (onequarter) of the resolution (2m×2n) of the physical pixel array, and thecolor image MCI has a form of the same resolution (m×n) as that of thecolor pattern information BP1, but example embodiments are not limitedthereto, and the configuration may be configured to have a differentresolution.

For example, the color pattern information BP1, the illuminance patterninformation BP2, and the color image MCI may be implemented to have adifferent resolution from that in other example embodiments, bydifferently configuring digital signal processing. In some exampleembodiments, the color pattern information BP1 and the illuminancepattern information BP2 may have the same resolution as that of thephysical pixel array (2m×2n).

In some embodiments, the color pattern information BP1 has the sameresolution as that of the pixel array (2m×2n), but the illuminancepattern information BP2 may have a resolution of ¼ of the resolution ofthe pixel array (2m×2n). In this case, the color image MCI has the sameresolution as the color pattern information BP1, and the merging processof the color pattern information BP1 and the illuminance patterninformation BP2 may be performed as a merging process of 4:1 (colorpattern: illuminance pattern) rather than one-to-one correspondence.

As illustrated in FIG. 2 , the image sensor 500 according to someexample embodiments may include a row driver 340 driven by a controlunit 300′ together with the pixel array 100, the signal processing unit200, and the control unit 300′.

As described above, the pixel array 100 may include a plurality ofpixels PX arranged in the unit of an extended Bayer pattern block EB anda plurality of pixel blocks PB. Each of the pixels PX may include acorresponding light sensing element. For example, the light sensingelement may be or include a photodiode. The plurality of pixels PXabsorb light to generate charge, and may provide an electrical signal(output voltage) to the signal reader 350, according to the generatedcharge may be.

The control unit 300′ may control the row driver 340 to enable the pixelarray 100 to absorb light to accumulate charge, temporarily storeaccumulated charge, and output an electrical signal according to thestored charge to the outside of the pixel array 100. Alternatively oradditionally, the control unit 300′ may control the signal reader 350 tomeasure the output voltage provided by the pixel array 100. The controlunit 300′ illustrated in FIG. 2 is/corresponds to a control unitresponsible for a control function configured to drive the pixel array100 and read signals, and may be understood as the control unit 300responsible for a portion of functions of the control unit illustratedin FIG. 1 .

The row driver 340 may generate signals such as RSs, TXs, and SELSs forcontrolling the pixel array 100, and provide the signals to theplurality of pixels PX included in the pixel array 100. The row driver340 may determine activation and deactivation timings of reset controlsignals RSs, transmission control signals TXs, and/or selection signalsSELSs for the plurality of pixels PX, and may provide other signals tothe plurality of pixels PX included in the pixel array 100.

The signal reader 350 may include a correlated double sampler (CDS) 351,an analog-to-digital (A/D) converter (ADC) 353, and/or a buffer 355. Thecorrelated double sampler 351 may sample and hold the output voltageprovided by the pixel array 100. The correlated double sampler 351 maydouble-sample a level according to a specific noise level and thegenerated output voltage, and may output a level corresponding to thedifference. Alternatively or additionally, the correlated double sampler351 may receive ramp signals generated by a ramp signal generator 357,and may compare the signals to output a comparison result. The A/Dconverter 353 may convert an analog signal corresponding to a levelreceived from the correlated double sampler 351 into a digital signal.The buffer 355 may latch digital signals, and the latched signals may besequentially output to the signal processing unit 200 and/or the outsideof the image sensor 500.

The signal processing unit 200 may perform signal processing on thereceived data of the plurality of pixels PX. In addition to the processof generating a Bayer pattern color image by combining a color patternand an illuminance pattern obtained through the above-described binning,the signal processing unit 200 may perform various image signalprocessing for image quality improvement, such as array interpolation,other noise reduction processing, gain adjustment, waveform shapingprocessing, and/or color filter array interpolation, white balanceprocessing, gamma correction, edge emphasis processing, and/or the like.Alternatively or additionally, the signal processing unit 200 may outputinformation regarding a plurality of pixels PX to a processor (notillustrated) during phase difference auto-focusing to perform phasedifference calculation (see FIGS. 8 to 11 ).

In some example embodiments, the signal processing unit 200 isillustrated as being implemented in a portion of the image sensor 500,in detail, in a logic circuit, but may also be implemented in aprocessor (not illustrated) separately provided outside of the imagesensor 500.

FIG. 6 is a partial plan view illustrating the pixel array illustratedin FIG. 1 .

Referring to FIG. 6 , a portion of the pixel array 100 illustrated inFIG. 1 , for example, one extended Bayer pattern block EB isillustrated.

The extended Bayer pattern block EB includes first to fourth pixelblocks PB1, PB2, PB3, and PB4 arranged in a 2×2 matrix (e.g. arrangedadjacently as illustrated and as described above), and the first tofourth pixel blocks PB1, PB2, PB3, and PB4 include first and fourthpixels PX1 and PX4 arranged diagonally, each of the first and fourthpixels PX1 and PX4 included in different pixel blocks PB1 to PB4receiving light of different colors, and second and third pixels PX2 andPX3 receiving white light, respectively.

The first to fourth pixel blocks PB1, PB2, PB3, and PB4 employed in someexample embodiments may include one floating diffusion FD shared by thefirst to fourth pixels PX1, PX2, PX3, and PX4, and transistors M1, M2,M3, and M4 (e.g. transfer transistors) disposed between the first tofourth pixels PX1, PX2, PX3, and PX4 and the floating diffusion FD. Thecharges accumulated in photodiodes PD1, PD2, PD3, and PD4 of the firstto fourth pixels PX1, PX2, PX3, and PX4 may be transmitted to thefloating diffusion FD, through the transistors M1, M2, M3, and M4connected to the photodiodes PD1, PD2, PD3 and PD4, respectively. Assuch, the four pixels PX1, PX2, PX3, and PX4 located in the same pixelblock PB1, PB2, PB3, and PB4 may share one floating diffusion FD. Whenone floating diffusion FD is shared as in some example embodiments, thesame color information may be read with a time difference. For example,some transistors M1 and M4 may simultaneously be turned ON to store andread green information from the photodiodes PD1 and PD4 in floatingdiffusion FD, and subsequently, some other transistors M2 and M3 may besimultaneously turned ON to store and read the illuminance (e.g., white)information from the photodiodes PD2 and PD3 in the floating diffusionFD.

In some example embodiments, the floating diffusion FD may be disposedto be shared by two adjacent same color pixels, such that two floatingdiffusions FD may be provided in one pixel block. For example, the greenpixels PX1 and PX4 may share one floating diffusion FD, and the whitepixels PX2 and PX3 may share the other floating diffusion FD. In thiscase, all the transistors M1 to M4 are simultaneously turned ON to storeinformation in two floating diffusions FD, and green information andwhite information may be simultaneously read.

FIG. 7 illustrates a circuit of the pixel block PB1 including fourpixels PX1, PX2, PX3, and PX4 illustrated in FIG. 6 , as a portion of apixel circuit corresponding to a pixel array.

The process of generating an image signal in each pixel will bedescribed with reference to FIG. 7 .

When light enters the pixel, charges depending on the amount of lightare generated in (within) the photodiodes PD1, PD2, PD3, and PD4 byphotoelectric conversion. The charges accumulated in the photodiodesPD1, PD2, PD3 and PD4 are transmitted to the floating diffusion FDthrough the transistors (transfer transistors) M1, M2, M3 and M4. Thetransistors M1, M2, M3 and M4 may be controlled by control signals oftransmission signal lines TR1, TR2, TR3, and TR4, respectively. Theoperation process may be described in detail with reference to FIG. 7 .

First, a reset signal RS is applied to the (reset) transistor M5 and thecharge accumulated in the floating diffusion FD is reset. When thecharge amount sufficiently reaches the reset level, a row select signalSL is applied to the transistor M4, and a source current of thetransistor M3 based on the charge amount of the floating diffusion FDflows to a column signal line SIG, and may be transmitted to an A/Dconverter 353 (see FIG. 6 ) as a reset level.

Next, the reset signal RS and the row select signal SL are turned OFF, atransmission signal TS is applied to the transistor M5, and the chargegenerated by the photodiode PD1 is transmitted to the floating diffusionFD. When the transmission is sufficiently completed, the column selectsignal SL is applied to the transistor M7, and a source current of thetransistor M6 based on the amount of charge of the floating diffusion FDflows to a row signal line SIG, and may be transmitted to the A/Dconverter (see A/D converter 313 in FIG. 2 ) as a pixel signal level. Inthe A/D converter, the correct pixel signal may obtain the correct pixelsignal by detecting a difference between the reset level and the pixelsignal level.

As such, in the pixel circuit according to some example embodiments, thetransistors M5, M6 and M7 together with the floating diffusion FD may beshared by the pixels PX1, PX2, PX3, and PX4 in (within) the same pixelblock.

In some example embodiments, in the pixel block PB of a 2×2 matrix, theexposure time of some pixels may be adjusted differently from theexposure time of other pixels. For example, the pixels PX1 and PX4 ofthe same color of the first to fourth pixel blocks PB1, PB2, PB3, andPB4 may be controlled with different exposure times. Similarly, the samewhite pixels PX2 and PX3 in each pixel block may be controlled withdifferent exposure times. This control may be performed by the controlunit 300′ illustrated in FIG. 2 ; however, example embodiments are notlimited thereto.

For example, the control unit (300 in FIG. 2 ) may control the pixelsPX1 and PX3 located in the 2m−1 (m≥1)-th row among the first to fourthpixels PX1, PX2, PX3 and PX4 by a first exposure time, and may controlthe pixels PX2 and PX4 positioned in the 2m-th row by a second exposuretime shorter than the first exposure time.

As such, the signal of the pixel by the first exposure time (e.g., along time) and the signal of the pixel by the second exposure time (ashort time) are synthesized by enabling the same color pixels of thesame pixel block to be different by the first and second exposure times,a wide dynamic range (WDR) may be provided, and the final color image(MCI) may be expressed in detail with light and dark areas.

FIG. 8 is a plan view illustrating a pixel array (including autofocusingpixels) according to an example embodiment, and FIG. 9 is across-sectional view illustrating an autofocusing pixel of the pixelarray illustrated in FIG. 8 .

Referring to FIGS. 8 and 9 , a pixel array 100A according to someexample embodiments may be understood to be similar to the pixel array100 of FIG. 3 except that it has a pixel (or a shared pixel for phasedetection) for autofocusing. Alternatively or additionally, thecomponents of this example embodiment may be understood by referring tothe description of the same or similar components of the pixel array 100described in FIGS. 1 to 3 , unless specifically stated to the contrary.

The pixel array 100A according to this example embodiment includes aplurality of pixels PXs disposed in a plurality of rows and a pluralityof columns, and may be arranged in the unit of a pixel block (PB) and anextended Bayer patterned block (EB) similarly to the pixel array 100illustrated in FIG. 3 . The plurality of pixels PX may include a sharedpixel AF for phase detection, for autofocusing.

The shared pixel AF for phase detection each includes first and secondphase detection pixels FD1 and FD2 for sensing light of the same color.For example, the first and second phase detection pixels FD1 and FD2 mayinclude pixels for sensing green light. Unlike the other pixels forobtaining image information, the first and second phase detection pixelsFD1 and FD2 may be used not only for an autofocusing function using aphase difference, but also for measurement of a distance between anobject and an image sensor.

Since the first and second phase detection pixels FD1 and FD2 aredisposed adjacent to each other and configured to sense the same color,the first and second phase detection pixels FD1 and FD2 may partiallydeviate from the regularity of the arrangement employed in the pixelarray according to this example embodiment. The information of pixelsoutside the regularity of the arrangement may be replaced withinformation of other adjacent pixels in the case of a signal processingprocess. For example, in the signal processing process, a second phasedetection pixel FD2 may be replaced with information of other whitepixels located in the same pixel block.

A plurality of shared pixels AF for phase detection may be disposed indifferent areas. In some example embodiments, the first and second phasedetection pixels FD1 and FD2 may include a pair arranged in a rowdirection and a pair arranged in a column direction.

In detail, referring to FIG. 9 , the first and second phase detectionpixels PD1 and PD2 include light sensing elements PD1 and PD2, lightshielding layers 108, an insulating layer 106, a color filter layer 107,and a micro lens 109, respectively. The light shielding layer 108employed in this example embodiment is disposed in the insulating layer106 and may include a reflective metal material. The light shieldinglayer 108 employed in this example embodiment may have a shape spanningbetween two pixels FD1 and FD2.

The light shielding layer 108 may block a portion of light incident tothe light sensing elements PD1 and PD2. A difference in the amount oflight received by the light sensing elements PD1 and PD2 may occurdepending on the incident direction of light. As described above, it maybe determined whether focusing is obtained based on the difference inthe amount of light received by the first and second phase detectionpixels FD1 and FD2. Based on this, a lens (not illustrated) may beadjusted to automatically focus. The shared pixel AF for phase detectionin which the first and second phase detection pixels FD1 and FD2 arearranged in the row direction are used to adjust the focusing in thehorizontal direction, and the shared pixel AF for phase detection inwhich the first and second phase detection pixels FD1 and FD2 arearranged in the column direction may be used to adjust the focus in thevertical direction.

FIG. 10 is a plan view illustrating a pixel array (includingautofocusing pixels) according to an example embodiment, and FIG. 11 isa cross-sectional view illustrating an autofocusing pixel of the pixelarray illustrated in FIG. 10 .

Referring to FIGS. 10 and 11 , a pixel array 100A′ according to someexample embodiments may be understood to be similar to the pixel array100A of FIGS. 8 and 9 except that the pixel structure for autofocusingis different. In addition, the components of these example embodimentsmay be understood by referring to the descriptions of the same orsimilar components of the pixel arrays 100 and 100A described in FIGS. 1to 3 and FIGS. 8 and 9 , unless otherwise specified.

The shared pixel AF for phase detection, used in the previousembodiment, is illustrated in the form of using the light shieldinglayer 108, but a shared pixel AF' for phase detection according to thisexample embodiment may include one micro lens 109′ configured to beshared by first and second phase detection pixels FD1′ and FD2′, ratherthan the light shielding layer 108.

The micro lenses 109′ shared by the first and second phase detectionpixels FD1′ and FD2′ may adjust incident light directed to respectivelight sensing elements PD1 and PD2. The first and second phase detectionpixels FD1 and FD2 may output different phase signals depending on theshape and/or refractive index of the micro lens 109′ employed in thisexample embodiment. Focus may be adjusted based on different phasesignals. Similar to some example embodiments, the shared pixel AF forphase detection in which the first and second phase detection pixels FD1and FD2 are arranged in the row direction is used to adjust the focus inthe horizontal direction, and the shared pixel AF for phase detection inwhich the first and second phase detection pixels FD1 and FD2 arearranged in the column direction may be used to adjust the focus in thevertical direction.

FIG. 12 is a plan view illustrating a pixel array employable in an imagesensor according to some example embodiments, and FIGS. 13A and 13Billustrate color information and illuminance information generated bysignal processing of an image sensor according to an example embodiment,respectively.

Referring to FIG. 12 , a pixel array 100B according to this exampleembodiment may be understood to be similar to the pixel array 100 ofFIG. 3 except that the pixel (or a shared pixel for phase detection) isprovided for autofocusing. In addition, the components of some exampleembodiments may be understood by referring to the descriptions of thesame or similar components of the pixel array 100 described in FIGS. 1to 3 , unless specifically stated to the contrary.

The pixel array 100B includes a plurality of pixels PX arranged in aplurality of rows and a plurality of columns, and similar to theprevious embodiment, may be arranged in the unit of the pixel blocksPB1, PB2, PB3, and PB4 and the extended Bayer pattern blocks (EB).

Referring to FIG. 12 , similar to the pixel array 100 illustrated inFIG. 3 , the pixel array 100B includes a plurality of extended Bayerpattern block (EB) having first to fourth pixel blocks PB1, PB2, PB3,and PB4, respectively arranged in a 2×2 matrix, but unlike the someexample embodiments, the first to fourth pixel blocks PB1, PB2, PB3, andPB4 may each include nine pixels PX arranged in a 3×3 matrix.

In each of the pixel blocks PB1, PB2, PB3 and PB4, 5 pixels PX arrangedin two diagonal directions DL1 and DL2 are configured to detect light ofcolor, and the remaining four pixels may be configured to detect whitelight. In detail, the five color pixels PX of the first and fourth pixelblocks PB1 and PB4 may be green pixels G configured to sense greenlight. The five color pixels PX of the second and third pixel blocks PB2and PB3 may be red and green pixels R and G configured to sense redlight and blue light, respectively. The four white pixels PX of thefirst to fourth pixel blocks PB1, PB2, PB3 and PB4 may be/correspond towhite pixels W configured to sense white light.

As described above, the “pixel block (PB1, PB2, PB3, PB4)” employed insome example embodiments may have various pixel arrangements in which aplurality of color pixels and a plurality of illuminance detectionpixels are combined, while an “extended Bayer pattern block (EB)” mayhave an R-G-G-B Bayer pattern in which four pixel blocks PB1, PB2, PB3and PB4 are arranged, similar to the previous embodiment.

Output signals of the pixel array 100 are binned into a color signalcomprised of RGB and an illuminance signal comprised of W in the binningpattern generation unit (240 in FIG. 1 ), and as illustrated in FIGS.13A and 13B, color pattern information BP1′ and illuminance patterninformation BP2′ are generated from the binned color and illuminancesignals, respectively. Subsequently, the color pattern information BP1′and the illuminance pattern information BP2′ may be merged in a patternmerging unit (see 280 of FIG. 1 ) to provide a color image having thesame resolution as the color pattern information BP1′.

Since one pixel block of the pixel array 100 generates one patterninformation of the color pattern information BP1′ and the illuminancepattern information BP2′, the color pattern information BP1′, theilluminance pattern information BP2′, and the final color image may havea resolution corresponding to an arrangement of pixel blocks. Forexample, when the number of the first to fourth pixel blocks PB1, PB2,PB3, and PB4 in the pixel array 100 in the row direction and the numberof the first to fourth pixel blocks PB1, PB2, PB3, and PB4 in the pixelarray 100 in the column direction are m and n, respectively, the Bayerpattern type color and illuminance information (BP1′, BP2′) and thefinal color image may each have a resolution of m×n.

The merging process may be performed in such a manner that patterns inpositions corresponding to each other in the color pattern informationBP1 and the illuminance pattern information BP2 are one-by-one mergedwith each other. Respective colors R, G, and B of the color patterninformation BP1′ may provide a color image having improved sensitivitycharacteristics by illuminance data at a corresponding position of theilluminance pattern information BP2.

As described above, according to some example embodiments, the colorpattern information BP1′ obtained from five pixels PX in each pixelblock improves, e.g. greatly improves sensitivity characteristics suchas SNR and DR by the binned illuminance pattern information BP2′, and asa result, a Bayer pattern color image having improved, or excellent,image quality may be output. Since respective pattern data of theilluminance pattern information BP2′ is information obtained from fourwhite pixels PX positioned adjacent in the same pixel block as the fivecolor pixels PX associated with the color signal to be merged, thesensitivity may be appropriately improved in accordance with theenvironment/neighborhood of the corresponding pixel.

In the above-described embodiment, although a pixel array provided as acombination of color pixels indicated by R, G and B, and illuminancesensing pixels indicated by W is illustrated, color pixels and/orilluminance sensing pixels may be partially changed. In some exampleembodiments, at least a portion of the color pixels may be changed toother colors. For example, pixels (in detail, filters) for detectingyellow, cyan, and/or magenta colors may be included. Alternatively oradditionally, the illuminance sensing pixel may be configured to detectlight in a wider band than the wavelength band of the color pixel. Forexample, the illuminance sensing pixel may include another pixel, forexample, a yellow pixel, in addition to the white pixel W. Alternativelyor additionally, the illuminance sensing pixel may be configured todetect light in a band larger than visible wavelength.

As set forth above, according to some example embodiments, a pixel arrayis constructed by appropriately combining color pixels that receivecolor (e.g., RGB) and an illuminance sensing pixel (e.g., white) forimproving sensitivity, and color pattern information and/or illuminancepattern information may be respectively generated by binning a signalobtained from the pixel array. The color pattern information may beprovided as a Bayer pattern, and the illuminance pattern information maybe configured as a pattern having illuminance information correspondingto respective pixel information one to one. The color pattern and theilluminance pattern may be merged to output a Bayer pattern color imagehaving improved image quality in terms of SNR and/or Dynamic Range (DR).

Each of, or at least some of, the elements described above, such as butnot limited to elements described as “units” or “devices”, such as thepattern merging unit 280, the control unit 300, the memory 400, and/orelements ending in “-er” or “-or”, may include processing circuitry suchas hardware including logic circuits; a hardware/software combinationsuch as a processor executing software; or a combination thereof. Forexample, the processing circuitry more specifically may include, but isnot limited to, a central processing unit (CPU), an arithmetic logicunit (ALU), a digital signal processor, a microcomputer, a fieldprogrammable gate array (FPGA), a System-on-Chip (SoC), a programmablelogic unit, a microprocessor, application-specific integrated circuit(ASIC), etc.

While some example embodiments have been illustrated and describedabove, it will be apparent to those of ordinary skill in the art thatmodifications and variations could be made without departing from thescope of example embodiments as defined by the appended claims.

What is claimed is:
 1. An image sensor comprising: a first 4×4 pixelarray including four green pixels, eight white pixels, two blue pixels,and two red pixels; and a second 4×4 pixel array including N greenpixels, M white pixels, two blue pixels, and two red pixels, wherein theN is an integer and greater than 4, and wherein the M is an integer andless than
 8. 2. The image sensor of claim 1, wherein the second 4×4pixel array includes a first autofocusing pixel and a secondautofocusing pixel.
 3. The image sensor of claim 2, further including amicrolens, and wherein the microlens is disposed on the first and secondautofocusing pixels.
 4. The image sensor of claim 3, wherein the firstand second autofocusing pixels are green pixels.
 5. The image sensor ofclaim 4, wherein a first blue pixel, a first white pixel, the firstautofocusing pixel and the second autofocusing pixel are arranged in oneof row of the second 4×4 pixel array.
 6. The image sensor of claim 5,wherein the first blue pixel and the first autofocusing pixel and thesecond autofocusing pixel are arranged sequentially in a firstdirection, and wherein the first blue pixel is disposed right next tothe first autofocusing pixel.
 7. The image sensor of claim 6, furthercomprising a third autofocusing pixel and a fourth autofocusing pixel,and wherein the third and fourth autofocusing pixels are green pixels,and wherein the first autofocusing pixel and the second autofocusingpixel are arranged in the first direction, and wherein the thirdautofocusing pixel and the fourth autofocusing pixel are arranged in asecond direction perpendicular to the first direction.
 8. The imagesensor of claim 6, wherein the second 4×4 pixel array includes a thirdautofocusing pixel and a fourth autofocusing pixel, and wherein thethird autofocusing pixel and the fourth autofocusing pixel are greenpixels.
 9. The image sensor of claim 8, wherein the first autofocusingpixel and the second autofocusing pixel are arranged in the firstdirection, and wherein the second autofocusing pixel and the thirdautofocusing pixel are arranged in a second direction perpendicular tothe first direction.
 10. An image sensor comprising: a 6×5 pixel arrayincluding a plurality of white pixels, a plurality of green pixels, aplurality of blue pixels, a plurality of red pixels, and first to fourthautofocusing pixels, and wherein the first and second autofocusingpixels, first and second white pixels, a first blue pixel, and a firstgreen pixel in the 6×5 pixel array are arranged in a first direction,and wherein the first green pixel, a third white pixel, a first redpixel, and a third autofocusing pixel in the 6×5 pixel array arearranged in a second direction perpendicular to the first direction. 11.The image sensor of claim 10, wherein the 6×5 pixel array furthercomprises a fourth autofocusing pixel, a second blue pixel, a fourthwhite pixel, a second green pixel, and fifth white pixel, and whereinthe third autofocusing pixel, the fourth autofocusing pixel, the secondblue pixel, the fourth white pixel, the second green pixel, and thefifth white pixel are arranged in the first direction.
 12. The imagesensor of claim 11, wherein the fifth white pixel, the second greenpixel, the fourth white pixel, the second blue pixel, the fourthautofocusing pixel, and the third autofocusing pixel are sequentiallyarranged in the first direction.
 13. The image sensor of claim 10,further comprising a microlens, and wherein the microlens is disposed onthe first autofocusing pixel and the second autofocusing pixel, andwherein the first and second autofocusing pixels are green pixels. 14.The image sensor of claim 13, further comprising a fifth white pixel, asecond red pixel, and sixth white pixel, and wherein the second greenpixel, the fifth white pixel, the sixth white pixel, and the second redpixel, and the second autofocusing pixel are arranged in the seconddirection.
 15. The image sensor of claim 14, wherein the secondautofocusing pixel, the fifth white pixel, the second red pixel, thesixth white pixel, and the second green pixel are sequentially arrangedin the second direction.
 16. The image sensor of claim 11, wherein the6×5 pixel array further comprising a fourth autofocusing pixel, andwherein the first to fourth autofocusing pixels are green pixels, andwherein the first and second autofocusing pixels are arranged in thefirst direction and the fourth and third autofocusing pixels arearranged in the first direction.
 17. The image sensor of claim 16,further comprising a microlens, and wherein the microlens is disposed onthe first autofocusing pixel and the second autofocusing pixel.
 18. Theimage sensor of claim 17, wherein the first autofocusing pixel isdisposed on a first corner out of four corners of the 6×5 pixel array,and wherein the third autofocusing pixel is disposed on a second cornerout of the four corners of the 6×5 pixel array, and wherein the firstcorner is located diagonally from the second corner.
 19. The imagesensor of claim 18, further comprising a fifth autofocusing pixel and asixth autofocusing pixel.
 20. An image sensor comprising: an 8×8 pixelarray including a plurality of white pixels, a plurality of greenpixels, a plurality of blue pixels, a plurality of red pixels, first toeighth autofocusing pixels, and first to fourth microlens, and whereinthe first microlens is disposed on the first and second autofocusingpixels, the second microlens is disposed on the third and fourthautofocusing pixels, the third microlens is disposed on the fifth andsixth autofocusing pixels, and the fourth microlens is disposed on theseventh and eighth autofocusing pixel, and wherein the first and secondautofocusing pixels are arranged in a first direction and the third andfourth autofocusing pixels are arranged in a second directionperpendicular to the first direction, and wherein the first to eighthautofocusing pixels are green pixels.